Objective: we aimed to detect the coronary artery disease in patients with systemic lupus erythematosus and scleroderma associated with pulmonary hypertension and its relation to disease activity. Methods: Twenty patients with systemic lupus erythematosus (10 with pulmonary hypertension, and another 10 with normal pulmonary artery pressure), and 20 patients with sclerderma (10 with pulmonary hypertension, and another 10 with normal pulmonary artery pressure) were included in this study. Stress technetium 99m myocardial perfusion imaging was done for all patients. Patients with positive scinigraphic study were subjected to coronary angiography to exclude coronary artery lesion. Results: Myocardial perfusion SPECT with a stress-rest protocol revealed that 7 patients had coronary artery disease, 3 (15%) patients with SLE and PH, 3 (15%) patients with scleroderma with PH, 1 (5%) patient with SLE with normal pulmonary artery pressure. There was high incidence of positive myocardial perfusion defects among SLE and SSc patients with pulmonary hypertension than those without. Coronary angiography revealed that only 1 sclerodrma patient with positive myocardial perfusion defect had coronary artery stenosis.Conclusion: Coronary artery disease is a common association with SLE and SSc patients especially those with pulmonary hypertension. It is important to determine the presence of subclinical coronary artery disease in patients with SLE.